Newegg via eBay offers the refurbished Motorola Arris Surfboard 600 Series DOCSIS 3.0 Broadband Cable Modem, model no. SB6183, for $49.99 with free shipping. That's $5 under our mention from three weeks ago and the lowest total price we've seen this year. (It's also $50 under the best price we could find for a new unit.) It features download speeds of more than 600Mbps and upload speeds of more than 100Mbps.
No clear warranty information is provided.